1. Field of the Invention
This invention relates to a device for forming a thin layer of dry one-component developer. Further, it relates to a device for forming a thin layer of non-magnetic developer.
2. Description of the Prior Art
Various dry type one-component developing devices have heretofore been proposed and put into practical use. However, in any of these developing systems, it has been very difficult to form a thin layer of dry one-component developer and therefore, the developing devices have been constructed for the formation of a relatively thick layer. Now that improvement of the sharpness, resolving power, etc. of the developed image is required, development of a method and device for forming a thin layer of dry one-component developer is requisite.
The heretofore known method of forming a thin layer of dry one-component developer is proposed in U.S. Pat. No. 4,292,387 and has been put into practical use. This has been concerned with the formation of a thin layer of magnetic developer. Magnetic developer requires a magnetic material to be added thereto to endow it with magnetism, and this leads to problems such as the poor fixativeness with which a developed image transferred to transfer paper is heat-fixed, the bad color during color reproduction which results from the addition of the magnetic material to the developer itself (the magnetic material is usually black), etc.
For this reason, as a method of forming a thin layer of non-magnetic developer, there has been proposed a method comprising making soft hair like beaver's hair into a cylindrical brush and applying developer to such brush or a method comprising applying developer to a developing roller having the surface thereof formed of fiber such as velvet by means of a doctor blade or the like.
However, where an elastic blade as the doctor blade is used with the fiber brush, control of the amount of developer is possible but uniform application of the developer cannot be achieved and frictional charging of developer particles present between the fibers of the brush is not effected with the blade merely frictionally contacting the fiber brush on the developing roller, and this has led to the problem that ghost or the like is liable to occur.